Mike Slaughter/Toronto Star via Getty ImagesCity in chaos: A Mexican sailor (right); rifle at the ready; keeps an eye out for looters as still-dazed residents of Mexico City explore the ruins of their historic city in the wake of two major earthquakes in 48 hours in September 1985.

Mike Slaughter/Toronto Star via Getty ImagesSelective devastation in downtown Mexico City is visible in this photo as some buildings withstood two violent earthquakes while others did not.

Cindy Karp/The LIFE Images Collection/GettyMass of wreckage from collapsed building.